Iraqi officials say Islamic State (IS) militants have destroyed a lock on the Euphrates River that served as a bridge in Ramadi as pro-government forces close in on the militant-held city to the west of Baghdad.

Iraqi forces have nearly surrounded Ramadi and have been moving into some neighborhoods of Ramadi, the capital of Anbar Province, during the last few days.

Iraqi Major General Ismail al-Mahlawi, the head of the government's military operations in Anbar Province, said the lock was the last remaining bridge from Ramadi's city center leading to the northwest.

He says the destruction of the bridge has left about 300 IS militants cut off and trapped in the city center.

IS militants seized Ramadi in May.

Backed by U.S.-led coalition air strikes, the pro-government forces earlier this week recaptured a military complex north of the city and a neighborhood on the city outskirts.